In the past, data processing devices have been available as a variety of pieces of electronic equipment, for example, a personal computer and a smartphone. In the data processing device, it desirably takes a short activation time from the moment when operating power is fed to a controller and the controller begins activation to the moment when the controller completes activation (the controller becomes able to run a program). By shortening the activation time, a feature of, for example, displaying an initial screen image can be immediately presented. Patent Document 1 discloses a technology for shortening an activation time by preparing a plurality of pieces of controller, dividing a sequence (i.e., procedure), which is needed for activation, into portions, allocating the portions to the pieces of controller, and allowing the pieces of controller to perform the allocated portions of the sequence in parallel. Patent Document 2 discloses a technology for shortening an activation time by preparing a sub (dedicated) controller, which takes a shorter activation time than main controller does, in place of the main controller that takes a longer activation time.